// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_ACCESSIBILITY_AX_TREE_SOURCE_H_
#define UI_ACCESSIBILITY_AX_TREE_SOURCE_H_

#include <stdint.h>

#include <vector>

namespace ui {

// An AXTreeSource is an abstract interface for a serializable
// accessibility tree. The tree may be in some other format or
// may be computed dynamically, but maintains the properties that
// it's a strict tree, it has a unique id for each node, and all
// of the accessibility information about a node can be serialized
// as an AXNodeData. This is the primary interface to use when
// an accessibility tree will be sent over an IPC before being
// consumed.
template <typename AXNodeSource, typename AXNodeData, typename AXTreeData>
class AXTreeSource {
public:
    virtual ~AXTreeSource() { }

    // Get the tree data.
    virtual AXTreeData GetTreeData() const = 0;

    // Get the root of the tree.
    virtual AXNodeSource GetRoot() const = 0;

    // Get a node by its id. If no node by that id exists in the tree, return a
    // null node, i.e. one that will return false if you call IsValid on it.
    virtual AXNodeSource GetFromId(int32_t id) const = 0;

    // Return the id of a node. All ids must be positive integers.
    virtual int32_t GetId(AXNodeSource node) const = 0;

    // Append all children of |node| to |out_children|.
    virtual void GetChildren(AXNodeSource node,
        std::vector<AXNodeSource>* out_children) const = 0;

    // Get the parent of |node|.
    virtual AXNodeSource GetParent(AXNodeSource node) const = 0;

    // Returns true if |node| is valid, and false if it's a null pointer or a
    // node object representing the null pointer.
    virtual bool IsValid(AXNodeSource node) const = 0;

    // Returns true if two nodes are equal.
    virtual bool IsEqual(AXNodeSource node1,
        AXNodeSource node2) const = 0;

    // Return a AXNodeSource representing null.
    virtual AXNodeSource GetNull() const = 0;

    // Serialize one node in the tree.
    virtual void SerializeNode(AXNodeSource node, AXNodeData* out_data) const = 0;

protected:
    AXTreeSource() { }
};

} // namespace ui

#endif // UI_ACCESSIBILITY_AX_TREE_SOURCE_H_
